Self inductance, Physics

Self inductance:

When current through a coil changes, the changing flux induces an emf that opposes the current flow.  This emf is the result of self inductance and is called 'back emf'.  The term 'self inductance' is often replaced merely by inductance.  The value of back emf is given by:

          E  =  -L x dl/dt  

Where L is the inductance in henries, and dl/dt the rate of change of current.

The minus indicates back emf.

The unit of inductance is the henry and is based on the equation.  If current changing at a rate of 1 amp a second induces an emf of 1 volt then the inductance is 1 henry. 

All circuits have inductance even a straight conductor, but if a straight piece of wire is formed into a coil the number of flux linkages increases and so does the inductance.

A further increase in inductance is achieved by increasing the flux density.  This depends on the area, the length of the coil and the permeability of material in which flux is established,

Thus,                  L    2257_self inductance.png=   Henries

                   N      =  Number of Turns

                   μo μr          =  Absolute Permeability

                   A       =  Area in square metres

                   I        =  Length of coil in metres (not wire)

As  reluctance (S) =  1903_self inductance1.png        μo μr A  =1/S       and     L  = N2/S

Also by transposition of E  =  -L  ×  dl/dt

          L  =  -E  ×  dl/dt


Posted Date: 9/13/2012 6:17:52 AM | Location : United States

Related Discussions:- Self inductance, Assignment Help, Ask Question on Self inductance, Get Answer, Expert's Help, Self inductance Discussions

Write discussion on Self inductance
Your posts are moderated
Related Questions
Regard as three resistors having three unique values of resistance. Presume the resistors are connected in series with each other. Additional suppose that the series combination of

The potential difference across a 4 ohm resistor is 20 volts.  Assuming that all of the energy dissipated by this resistor is in the form of heat, how many joules of heat are radia

State Huygens' Principle. With the help of a suitable diagram, prove Snell's law of refraction using Huygens' Principle.

what multiplication fact can be found by using the arrays or 2times9 and 5times9?

Three capacitors with different capacitances are connected in series.  Which of the following statements is TRUE? a) All three of the capacitors have the same potential diffe

PROJECTILE: "When a body is thrown upward making a particular angle 'Q' with the horizontal and moves freely under the action of gravity, it is known as a projectile". EXAMP

1.A=the set of whole numbers less tan 4 ? 2.B=the set of prime numbers less than 19 ? 3.C=the set of first three days of week?

Neuroscience is a scientific study of the nervous system. Usually, neuroscience has been seen considered as a branch of biology. Thus, it is now present an interdisciplinary scien

what is radius of curvature?